Must be regional, in Indiana the difference between a hoedown and a hootenanny is quite obvious, here you have a hoedown, in Russia a hoe has you down.
I never did understand the difference between a hijack and a sidebar though 
As far as a hootenanny though, such a thing occurs when, say some old man gets a particular tune in his head and starts tapping it out, grooving to a jive beat:
At first he starts slow, wagging a finger, tapping his toes, then gets to a particulary animated part and starts tapping away on your thumb. It’s sort of annoying but you swat him away and go back to watching CNN. Not to be discouraged he proceeds to start drumming on your shoe like Charlie Watts. You give him a little kick and, in an inspired frenzy he starts using your knees for bongos. “That’s It!”, you exclaim, “Get OUT NOW!”. He taps out a syncopated riff on the door as he opens it and steps outside. Passing your grandmother on the porch he treats her to a little drum roll on her new hairdo and she boots him down the steps into the yard. Lying on the ground he notices a couple of twigs left there by some dog, who had gone inside to get a bone. The old man picks up the sticks and lays there for a moment, putting himself back into the groove by air drumming on some clouds. He then pops up and heads toward the sidewalk, pausing long enough to bang out a nice Buddy Guy solo on the gate as he wanders out into the road and gets run over by a truck. Later, in the hospital, an old man lays in a coma while you stand there overcome with guilt for kicking him out. All he wanted to do was enjoy the beat man, just enjoy the beat. Suddenly the monitor flatlines and you feel a cold shiver run down your spine. A cold, yet somehow familiar, shiver that paradiddles up your back, and you find comfort in the fact, that this old man is going to knick-knack once again in a better place.
The morel of the story, take the time to enjoy the beat man, it don’t last forever 
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